In the 24 hours since, I've had a chance to kick the Preview's tires a bit and look under the hood, employing the jaundiced eye of a longtime Windows veteran who isn't the least bit impressed with Windows 8's Jekyll-and-Hyde approach. What I see leaves me more convinced than ever that Microsoft is running Windows into the ground.

If you're forced to use Windows 8 or if you're one of the 1 percent (OK, 5 percent) who actually prefer Win8 over Win7, Windows 8.1 and Windows RT 8.1 are shaping up to be must-have updates.

On the Metro side, Microsoft has heaped loads of features that should have been in the original release: more PC Settings options, resizable Metro Snap panes, better SkyDrive integration. You'll also find the kind of cosmetic surgery you should expect in a version 2.0 product, such as different sizes for live tiles, more colors and patterns, and a few new Charms options.

On the old-fashioned Desktop, we get a new Start button, from which one can actually shut down or reboot the system, and a way to disable the hot corners for the running apps list on the left and the Charms bar on the right. I find it interesting -- disturbing, really -- that one of the two major Desktop improvements is the ability to disable overbearing Windows 8 features.

For both Metro-philes and Metro-phobes, we have a new boot-to-desktop option and a remarkably upgraded Internet Explorer 11. Of course, most of us are still struggling with IE10 on Windows 7 -- or even IE8 on WinXP. No word yet on whether IE11 will be released for Win7. SkyDrive is built-in. You don't need to install a separate app, and Windows RT users finally get access to the full product.

While most of the features in Windows 8.1 should have been in Windows 8, my hat's off to the engineering work done on the update. Microsoft has put together an enormous number of improvements, and it's well on the way to shipping them in less than a year. That has to be the fastest "version 2.0" of a major product in Microsoft history. Plus, it establishes a cadence of annual, substantive updates that Microsoft claims it can maintain.

You can install and run the beta, but it would be wise to understand the limitations first. The final version of Windows 8.1 is widely expected in August or possibly September.

Metro improvementsNew Start screen live tiles. In addition to the Win8 square and doublewide rectangular tiles, Win8.1 adds quarter- and quadruple-size tiles (see Figure 1). An individual tile's background colors can be changed if the tile isn't "live" (in theory -- I couldn't get it to work in the beta).

Figure 1. Metro now offers four different tile sizes.

New Start screen backgrounds. The very limited set of Win8 Start screen colors and swirls have multiplied enormously, and some of the new ones move. You can set a picture as a Start screen background or specify a set of folders for a slideshow. You can even copy the old-fashioned Desktop's background and use it on the Start screen. That's supposed to make the transition from Desktop to Start screen less jarring.